Steel Joists and Joist Girders
Description
Steel joists, also known as open-web steel joists, offer advantages over traditional, less durable systems in terms of load capacity and span conditions. They are lightweight, cost-effective alternatives for framing floors and roofs in building construction. With a diverse range of designations, steel joists can span up to 144′ and have depths ranging from 8″ to 120″.
Our services
We are an experienced, SJI-certified steel joist fabricator and can offer you K, KCS and LH series joists and girders.
Our knowledgeable and skilled staff will assist you in selecting the optimal joists and girders for your projects. We are dedicated to fabricating and delivering all the necessary components for the installation of your joists, girders, and bridging in your structures.
Each of your orders will include the following items:
- K Joist
- KCS Joist
- LH Joists
- Joist Girders
SJI-certified open web steel joists
Steel Joist Series We Fabricate
Every open web steel joist we ship is designed and fabricated to Steel Joist Institute (SJI) specifications. Choose the series by span, depth and load, or send us your drawings and our team will recommend the most economical option.
Standard open web joists
K-Series Steel Joists
K-Series joists are the standard bar joist used in most commercial roofs and floors. Their parallel chords and open web make them light, fast to erect and easy to run ductwork, piping and conduit through.
They are the most economical choice for short to medium spans with uniformly distributed loads, and are specified by depth, series and load designation (for example, 24K8).
- Depth range
- 8″ to 30″
- Typical span
- 20′ to 50′
- Maximum span
- Up to 60′ (SJI)
- Load type
- Uniformly distributed roof and floor loads
- Best for
- Economical framing of short to medium spans
K-Series Constant Shear
KCS Joists for Concentrated Loads
KCS joists share the depths of the K-Series but are designed for a constant moment and shear capacity along the full length. That lets them carry concentrated or non-uniform loads at almost any point without a special design.
They are the go-to option when the exact location of a load is unknown at bid time, or when a roof carries equipment, hung loads or cantilevers.
- Depth range
- 10″ to 30″
- Typical span
- 20′ to 50′
- Maximum span
- Up to 60′ (SJI)
- Load type
- Concentrated and non-uniform loads
- Best for
- Roofs with equipment or loads in unknown locations
Longspan & Deep Longspan
LH and DLH Series Longspan Joists
LH (Longspan) and DLH (Deep Longspan) steel joists cover the large, column-free areas that K-Series can't reach. LH joists handle long spans and heavier loads; DLH joists go deeper to clear the widest roofs.
Both can be fabricated with pitched top chords for roof drainage, and are commonly paired with joist girders to create very large bays with few interior columns.
- Depth range
- LH: 18″ to 48″
DLH: 52″ to 120″ - Typical span
- LH: 50′ to 90′
DLH: 90′ to 144′ - Maximum span
- LH up to 96′ · DLH up to 144′ (SJI)
- Load type
- Heavy roof and floor loads over long spans
- Best for
- Large column-free buildings
Quick comparison
Steel Joist Series at a Glance
Use this table as a starting point. Final selection depends on loads, deflection limits and project specs.
| Series | Depth range | Typical span | Max span (SJI) | Common use |
|---|---|---|---|---|
| K | 8″–30″ | 20′–50′ | 60′ | Standard roofs and floors |
| KCS | 10″–30″ | 20′–50′ | 60′ | Concentrated or unknown loads |
| LH | 18″–48″ | 50′–90′ | 96′ | Long spans, heavier loads |
| DLH | 52″–120″ | 90′–144′ | 144′ | Very long, column-free roofs |
| Joist Girder | 20″–120″ | 30′–60′ bays | Per design | Primary members supporting joists |
Typical spans are general guidance; maximum spans follow SJI standard specifications. Contact our estimating team for a project-specific recommendation.
Primary framing
Joist Girders
A joist girder is a primary open web member that spans between columns and supports joists at evenly spaced panel points. It replaces heavier wide-flange beams, reducing steel weight and erection time while allowing larger bays.
Joist girders are designed for the exact loads delivered by the joists they carry, so their size is defined by a simple designation:
Example: a 48G8N10K is a 48″ deep joist girder with 8 joist spaces and a 10-kip load at each panel point.
- Depth range
- 20″ to 120″
- Typical bay
- 30′ to 60′ between columns
- Supports
- K, KCS, LH and DLH joists
- Advantage
- Lighter than wide-flange beams, faster to erect
- Best for
- Warehouses, industrial and large retail buildings
Frequently asked questions
Steel Joist FAQs
Quick answers to the questions we hear most from contractors, engineers and owners.
What is a bar joist?
"Bar joist" is the common name for an open web steel joist: a lightweight truss with top and bottom chords connected by a web of diagonal members. The name comes from early joists that used round steel bars for the web. Today they are made from angles and other shapes, but the term is still widely used, especially for K-Series joists.
K vs LH series: what's the difference?
K-Series joists are 8″ to 30″ deep and are used for short to medium spans, up to 60′, with standard roof and floor loads. LH (Longspan) joists are 18″ to 48″ deep and carry heavier loads over longer spans, up to 96′. As a rule of thumb, K-Series is the economical choice up to roughly 50′, while LH takes over for larger, column-free areas. For spans beyond that, DLH joists go up to 144′.
How far can a steel joist span?
It depends on the series. Under SJI specifications, K-Series and KCS joists can span up to 60′, LH joists up to 96′ and DLH joists up to 144′. The practical span for your project depends on the load, the allowable deflection and the joist depth; a common starting point is a depth of about 1/2″ per foot of span for roofs.
Ready to quote
Need Steel Joists or Joist Girders for Your Project?
Send us your drawings and our estimating team will recommend the right series and deliver a fast, competitive quote.